Chlorosulfonated polyethylene elastomers are prepared commercially by dissolving polyethylene in a solvent such as carbon tetrachloride, along with a catalyst, and bubbling chlorine and sulfur dioxide therethrough to obtain polymers normally containing 20 to 40 percent chlorine and about 1 to 2 percent sulfur. The chlorosulfonated polyethylene is then isolated from the reaction media and dried. These polymers normally are substantially free of SO.sub.2. In a promising method for chlorosulfonating polyolefins that does not have some of the problems encountered with solution methods, such as the large volumes of liquid material that must be handled, problems of recovering and recycling toxic solvents; powdered polyolefins are chlorosulfonated with a mixture of chlorine and sulfur dioxide in the vapor phase, preferably in a fluidized bed. While this has been successfully achieved, some difficulty has been experienced in removing all of the residual sulfur dioxide from the resulting chlorosulfonated polyolefin powder, even after prolonged purging or degassing of the chlorosulfonated polymers at elevated temperatures. It has been found that these chlorosulfonated polyolefins, after packaging, still release objectionable amounts of sulfur dioxide gas in the packages. A method is needed to reduce release of free sulfur dioxide from sulfur dioxide containing vapor phase chlorosulfonated polyolefins, either while packaged, or thereafter, and eliminates the sulfur dioxide odor.